嚴重: Servlet.service() for servlet dispatcherServlet threw exception java.lang.IllegalStateException:

嚴重: Servlet.service() for servlet dispatcherServlet threw exception

java.lang.IllegalStateException: getOutputStream() has already been called for this response

at org.apache.catalina.connector.Response.getWriter(Response.java:610)
at org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:198)

這問題困擾了我好久都沒解決，最近這個項目中我又遇到了，下定決心一定要解決掉，這個異常時因為response.getOutputStream()跟response.getWriter()相衝突造成的,也可能是上次使用的資訊未清除，所以需要重設下緩衝。在使用之前加上response.resetBuffer();
現在記錄下，發出來和大家共用下，希望能幫到遇到同樣問題的朋友們，附下代碼：

private HttpServletResponse response;    private String encoding = "UTF-8";    private int blockSize = 1024;    private final Log logger = LogFactory.getLog(getClass());

/** * 輸出資料流到用戶端 * * @param inputStream 輸入資料流 * @param destFileName 另存名 * @throws java.io.IOException */public void write(InputStream inputStream, String destFileName) throws IOException {    this.response.resetBuffer();//重設輸出資料流，清空上次遺留資訊，防止報錯    this.response.setContentType("application/octet-stream");    this.response.setCharacterEncoding(this.encoding);    String downLoad = "";    if (destFileName != null) {        downLoad = new String(destFileName.getBytes("GBK"), "ISO-8859-1");    }    this.response.setHeader("Content-disposition", "attachment;filename=\"" + downLoad + "\"");    OutputStream output = null;    try {        byte[] bytes = new byte[blockSize];        output = this.response.getOutputStream();        int byteRead;        while ((byteRead = inputStream.read(bytes)) != -1) {            output.write(bytes, 0, byteRead);        }        output.flush();    }    catch (Exception ex) {        if (this.response.isCommitted()) {            logger.error("exception class:" + ex.getCause().getClass().getName() + "\nexception message:" + ex.getCause().getMessage());        }        throw new IOException(ex.getMessage());    }    finally {        if (inputStream != null){try{   inputStream.close();}            catch (Exception e) {                logger.error(e.getMessage());            }        }        if (output != null) {            try{                output.close();            }            catch (Exception e) {                logger.error(e.getMessage());            }        }        response.flushBuffer();    }}